BS (Biotechnology & Informatics).
Handouts:
Cell Biology.
BSCB-125.
References:
1. Cell and Molecular Biology Concepts and Experiments Gerald
Karp.
2. CELL BIOLOGY A Short Course SECOND EDITION (Stephen R.
Bolsover Department of Physiology University College London
Jeremy S. Hyams Department of Biology University College
London Elizabeth A. Shephard Department of Biochemistry and
Molecular Biology University College London Hugh A. White
Department of Biochemistry and Molecular Biology University
College London Claudia G. Wiedemann Department of
Physiology University College London)
3. Alberts - Molecular Biology of the Cell.
4. www.biology4kids.com
BSCB-125 Cell Biology
,BS (Biotechnology & Informatics).
THE CELL
The cell is the smallest structural and functional unit of the all living organisms. Cell biology is the study of the cell.
Cell biology is also known as cytology. The word cytology was derived from Greek word Kitos (cytos) means a halo
vessel or a compartment and Logus means to discover or to study. Therefore cytology literally means a branch of
biology which studies the different aspects of cells, like study of phenomenon of heredity, variation, evolution,
neutrition, metabolism, growth, reproduction of cell, etc.
History
1. In 1665, Robert Hook first time observed the cell. He observed a thin slice of cork under his own microscope.
Under microscope, he observed a honey-comb like structure showing hallow empty spaces or compartments
surrounded by firm cell wall. To each hallow space he called a ‘cell’. Actually what Robert Hook observed was dead
cell.
2. Antony Van Leeuwenhoek (1632–1723) observed first time the microorganisms (prokaryotic cell) under his
compound microscope. He observed tiny microbes in a drop of pond water which he called animacules.
3. In 1831, Robert Brown, first time observed a nucleus in the cell.
4. In 1855 Rudolph Virchow observed that new cells arise from preexisting cells.
5. In 1938, M.J. Schleiden, a German botanist studied many plants section under microscope and came to
conclusion that, “all plants are ultimately made up of cell”.
6. In 1938 T.S. Schwann, a German Zoologist came to the similar conclusion that, “all the animals are ultimately
made up of cell”. Later, Schleiden and Schwann both together put forth a theory which is known as a cell theory.
According to this theory all the organisms i.e. plants and animals are made up of cells.
In twentieth century, after the invention of modern microscopes and various technique, our knowledge of cell
increased and a statement of cell theory was slightly modified. According to the latest cell theory, “all the living
organisms consists of cells and cell products”. Therefore all the living organisms i.e. prokaryotic and eukaryotic
organisms are made up of cells. Viruses are not made up of cells. In unicelluar organisms, all functions are carried
out by the same cell, while in multicellular organisms, different functions are performed by different types of cells.
The cell theory may be summarised as
(a) Cells of organisms are differentiated into distinct cell types.
(b) A cell is a feature of all organisms with the exception of viruses.
(c) The protoplasm is the living content of the cell and determines the activity of the cell and thus the whole
organism.
(d) New cells originate from preexisting cells through division. In any case, cell never arise de novo. All living
cells/organisms have a common ancestor. Therefore, all cells shows common simplicity in the molecular
organization and principle of molecular economy.
Cell Size—There seems no generalization in size, shape and structure of the cell. The variety and diversity of cells
BSCB-125 Cell Biology
,BS (Biotechnology & Informatics).
Cell shape—Cell shape is controlled by certain physical, chemical and physiological factors. Majority of cells have
characteristic fixed shape. While certain cells have no fixed shape called variable cells, for e.g., amoeba and
leucocytes. Generally multicellular organisms are made up of different shaped cells.
Types of cells:
Depending upon their organisation, cells are basically of two types i.e., prokaryotic cells and eukaryotic cells.
Prokaryotic cells are primitive type of cells. These cells lacks true nucleus and other cell organelle like
mitochondria, chloroplasts, endoplasmic reticulum, golgi complex, etc. The word prokaryotes is derived from
Greek word pro means primitive or old and karyotes means nucleus or main. Eukaryotic cells have true nucleus
and it also contains cell organelles. The word eukaryotes is derived from Greek word eu means true and karyotes
means nucleus.
Prokaryotic cell Eukaryotic cell
A true nucleus is absent. A true nucleus is present.
Nuclear membrane is absent. Nuclear membrane is present.
Nucleolus is absent. Nucleolus is present.
Chromosome is single, circular. Chromosomes are many and linear.
Chromosome present freely in the cytoplasm. Chromosomes are enclosed inside the nuclear
membrane.
Histone proteins are absent in the organisation of Chromosomes are well organised with histone protein.
chromosome.
In photosynthetic cells, chlorophyll pigments are In photosynthetic cells, the chlorophyll pigments are
present in cell membrane. present in the plastids—chloroplast.
Ribosomes are 70s type. Ribosomes are 80s type.
Cell organells are absent. Cell organells are present.
Streaming or amoeboid movement of cytoplasm absent Streaming or amoeboid movement of cytoplasm
present.
Flagella if present, do not have typical 9 + 2 Flagella shows typical 9 + 2 arrangement.
arrangement.
Enzymes necessary for respiration are present in plasma Enzymes necessary for respiration are present in
membrane. mitochondria.
Cell division by the process of amitosis i.e., mitosis and Cell division by the process of mitosis and meiosis.
meiosis is absent.
mRNA will not have the 5' methyl cap and 3' poly A tail. mRNA having 5' methyl cap and 3' poly A tail.
Transcription and translation are combined process, Transcription and translation are not combined process.
both takes place in cytoplasm. Transcription takes place in nuclers, while translation
BSCB-125 Cell Biology
, BS (Biotechnology & Informatics).
occurs in cytoplasm.
In genes non-coding regions are absent. In genes non-coding region (i.e., introns) are present.
After transcription there is no post transcriptional After transcription, post transcriptional modifications
modification in mRNA. occurs in mRNA.
Polycistronic mRNA. Mono cistronic mRNA.
The cell wall contains amino sugars When cell wall present, it doesnot contain amino sugar
and muramic acid. and muramic acid.
Ultrastructure of Eukaryotic cell—Eukaryotic cells are highly evolved cells and show striking characters in contrast
to prokaryotes. It contains specialised membrane bound cell organelles. The most important cell organelle is
nucleus, which is membrane bound and includes filamentous chromosomes. Other membrane bound organelles
include chloroplants, mitochondria, lysosomes, golgi complex, endoplasmic reticulum, etc. The cell organelles
provides micro environments to subcellular metabolic units. The eukaryotic organisms are very diverse, few are
unicellular, where all the functions are carried out by same cell, while many are multicellular organisms.
Multicellular eukaryotes contains variety of cell types originate as a result of cell differentiation and it’s organized
aggregates, forming tissue systems. Although there is a basic pattern of organisation, several functional
specializations are acquired by cells. Eukaryotes are grouped into phototrophs (e.g., plants) and chemotrops (e.g.,
animals). The phototrophs have a photosynthetic apparatus and a rigid cell wall of cellulose.
Photosynthetic Eukaryotes—The eukaryotes, which are able to synthesize their own food in presence of the
sunlight is called— Photosynthetic Eukaryotes. As an example of this we can consider a typical plant cell. A plant
cell has a thick outer most coating called cell wall, which protect the cell from various osmatic stresses. Cell wall is
made up of cellulose. Inside the cell wall, there is a plasma membrane which encloses the cytoplasm. At several
locations, two adjacent cells have intercellular channels called plasmodesmata, which help cellular communication.
The Cytoplasm:
The cytoplasm of plant cell is semifluid, in which many cell organelles micro and macroneutrients and enzymes are
suspended. All cell organelles are bound by double membrane. Different cell organelles which are present in plant
cell are as follows;
(a) Nucleus—Nucleus is bounded by double layered nuclear membrane. It contains filamentous
chromosomes, which contains genetic information.
(b) Endoplasmic reticulum—The endoplasmic reticulum forms a network of tubules whose one end is
connected with nuclear membrane. There are two types of endoplasmic reticulum—smooth endoplasmic
reticulum and rough or granular endoplasmic reticulum. The main function of endoplasmic reticulam is
synthesis and storage of protein/ enzymes.
(c) Golgi complex—It is made up of cisternae and vesicles. It’s main function is storage.
(d) Mitochondria—Mitochondria synthesize ATP molecule (energy curency of cell) by oxidative
phosphorylation in the absence of light by breaking down organic molecules.
(e) plastids—Plastids are characteristic of plant cells only. Plastids are of two types—leucoplasts (with out
pigment) and chromoplasts (with pigments). The most important plastid is with green chlorophyll pigment
called chloroplasts. Chloroplasts participate in the photosynthetic activity.
(f) Lysosomes—It contains hydrolytic enzymes for digestion.
BSCB-125 Cell Biology
Handouts:
Cell Biology.
BSCB-125.
References:
1. Cell and Molecular Biology Concepts and Experiments Gerald
Karp.
2. CELL BIOLOGY A Short Course SECOND EDITION (Stephen R.
Bolsover Department of Physiology University College London
Jeremy S. Hyams Department of Biology University College
London Elizabeth A. Shephard Department of Biochemistry and
Molecular Biology University College London Hugh A. White
Department of Biochemistry and Molecular Biology University
College London Claudia G. Wiedemann Department of
Physiology University College London)
3. Alberts - Molecular Biology of the Cell.
4. www.biology4kids.com
BSCB-125 Cell Biology
,BS (Biotechnology & Informatics).
THE CELL
The cell is the smallest structural and functional unit of the all living organisms. Cell biology is the study of the cell.
Cell biology is also known as cytology. The word cytology was derived from Greek word Kitos (cytos) means a halo
vessel or a compartment and Logus means to discover or to study. Therefore cytology literally means a branch of
biology which studies the different aspects of cells, like study of phenomenon of heredity, variation, evolution,
neutrition, metabolism, growth, reproduction of cell, etc.
History
1. In 1665, Robert Hook first time observed the cell. He observed a thin slice of cork under his own microscope.
Under microscope, he observed a honey-comb like structure showing hallow empty spaces or compartments
surrounded by firm cell wall. To each hallow space he called a ‘cell’. Actually what Robert Hook observed was dead
cell.
2. Antony Van Leeuwenhoek (1632–1723) observed first time the microorganisms (prokaryotic cell) under his
compound microscope. He observed tiny microbes in a drop of pond water which he called animacules.
3. In 1831, Robert Brown, first time observed a nucleus in the cell.
4. In 1855 Rudolph Virchow observed that new cells arise from preexisting cells.
5. In 1938, M.J. Schleiden, a German botanist studied many plants section under microscope and came to
conclusion that, “all plants are ultimately made up of cell”.
6. In 1938 T.S. Schwann, a German Zoologist came to the similar conclusion that, “all the animals are ultimately
made up of cell”. Later, Schleiden and Schwann both together put forth a theory which is known as a cell theory.
According to this theory all the organisms i.e. plants and animals are made up of cells.
In twentieth century, after the invention of modern microscopes and various technique, our knowledge of cell
increased and a statement of cell theory was slightly modified. According to the latest cell theory, “all the living
organisms consists of cells and cell products”. Therefore all the living organisms i.e. prokaryotic and eukaryotic
organisms are made up of cells. Viruses are not made up of cells. In unicelluar organisms, all functions are carried
out by the same cell, while in multicellular organisms, different functions are performed by different types of cells.
The cell theory may be summarised as
(a) Cells of organisms are differentiated into distinct cell types.
(b) A cell is a feature of all organisms with the exception of viruses.
(c) The protoplasm is the living content of the cell and determines the activity of the cell and thus the whole
organism.
(d) New cells originate from preexisting cells through division. In any case, cell never arise de novo. All living
cells/organisms have a common ancestor. Therefore, all cells shows common simplicity in the molecular
organization and principle of molecular economy.
Cell Size—There seems no generalization in size, shape and structure of the cell. The variety and diversity of cells
BSCB-125 Cell Biology
,BS (Biotechnology & Informatics).
Cell shape—Cell shape is controlled by certain physical, chemical and physiological factors. Majority of cells have
characteristic fixed shape. While certain cells have no fixed shape called variable cells, for e.g., amoeba and
leucocytes. Generally multicellular organisms are made up of different shaped cells.
Types of cells:
Depending upon their organisation, cells are basically of two types i.e., prokaryotic cells and eukaryotic cells.
Prokaryotic cells are primitive type of cells. These cells lacks true nucleus and other cell organelle like
mitochondria, chloroplasts, endoplasmic reticulum, golgi complex, etc. The word prokaryotes is derived from
Greek word pro means primitive or old and karyotes means nucleus or main. Eukaryotic cells have true nucleus
and it also contains cell organelles. The word eukaryotes is derived from Greek word eu means true and karyotes
means nucleus.
Prokaryotic cell Eukaryotic cell
A true nucleus is absent. A true nucleus is present.
Nuclear membrane is absent. Nuclear membrane is present.
Nucleolus is absent. Nucleolus is present.
Chromosome is single, circular. Chromosomes are many and linear.
Chromosome present freely in the cytoplasm. Chromosomes are enclosed inside the nuclear
membrane.
Histone proteins are absent in the organisation of Chromosomes are well organised with histone protein.
chromosome.
In photosynthetic cells, chlorophyll pigments are In photosynthetic cells, the chlorophyll pigments are
present in cell membrane. present in the plastids—chloroplast.
Ribosomes are 70s type. Ribosomes are 80s type.
Cell organells are absent. Cell organells are present.
Streaming or amoeboid movement of cytoplasm absent Streaming or amoeboid movement of cytoplasm
present.
Flagella if present, do not have typical 9 + 2 Flagella shows typical 9 + 2 arrangement.
arrangement.
Enzymes necessary for respiration are present in plasma Enzymes necessary for respiration are present in
membrane. mitochondria.
Cell division by the process of amitosis i.e., mitosis and Cell division by the process of mitosis and meiosis.
meiosis is absent.
mRNA will not have the 5' methyl cap and 3' poly A tail. mRNA having 5' methyl cap and 3' poly A tail.
Transcription and translation are combined process, Transcription and translation are not combined process.
both takes place in cytoplasm. Transcription takes place in nuclers, while translation
BSCB-125 Cell Biology
, BS (Biotechnology & Informatics).
occurs in cytoplasm.
In genes non-coding regions are absent. In genes non-coding region (i.e., introns) are present.
After transcription there is no post transcriptional After transcription, post transcriptional modifications
modification in mRNA. occurs in mRNA.
Polycistronic mRNA. Mono cistronic mRNA.
The cell wall contains amino sugars When cell wall present, it doesnot contain amino sugar
and muramic acid. and muramic acid.
Ultrastructure of Eukaryotic cell—Eukaryotic cells are highly evolved cells and show striking characters in contrast
to prokaryotes. It contains specialised membrane bound cell organelles. The most important cell organelle is
nucleus, which is membrane bound and includes filamentous chromosomes. Other membrane bound organelles
include chloroplants, mitochondria, lysosomes, golgi complex, endoplasmic reticulum, etc. The cell organelles
provides micro environments to subcellular metabolic units. The eukaryotic organisms are very diverse, few are
unicellular, where all the functions are carried out by same cell, while many are multicellular organisms.
Multicellular eukaryotes contains variety of cell types originate as a result of cell differentiation and it’s organized
aggregates, forming tissue systems. Although there is a basic pattern of organisation, several functional
specializations are acquired by cells. Eukaryotes are grouped into phototrophs (e.g., plants) and chemotrops (e.g.,
animals). The phototrophs have a photosynthetic apparatus and a rigid cell wall of cellulose.
Photosynthetic Eukaryotes—The eukaryotes, which are able to synthesize their own food in presence of the
sunlight is called— Photosynthetic Eukaryotes. As an example of this we can consider a typical plant cell. A plant
cell has a thick outer most coating called cell wall, which protect the cell from various osmatic stresses. Cell wall is
made up of cellulose. Inside the cell wall, there is a plasma membrane which encloses the cytoplasm. At several
locations, two adjacent cells have intercellular channels called plasmodesmata, which help cellular communication.
The Cytoplasm:
The cytoplasm of plant cell is semifluid, in which many cell organelles micro and macroneutrients and enzymes are
suspended. All cell organelles are bound by double membrane. Different cell organelles which are present in plant
cell are as follows;
(a) Nucleus—Nucleus is bounded by double layered nuclear membrane. It contains filamentous
chromosomes, which contains genetic information.
(b) Endoplasmic reticulum—The endoplasmic reticulum forms a network of tubules whose one end is
connected with nuclear membrane. There are two types of endoplasmic reticulum—smooth endoplasmic
reticulum and rough or granular endoplasmic reticulum. The main function of endoplasmic reticulam is
synthesis and storage of protein/ enzymes.
(c) Golgi complex—It is made up of cisternae and vesicles. It’s main function is storage.
(d) Mitochondria—Mitochondria synthesize ATP molecule (energy curency of cell) by oxidative
phosphorylation in the absence of light by breaking down organic molecules.
(e) plastids—Plastids are characteristic of plant cells only. Plastids are of two types—leucoplasts (with out
pigment) and chromoplasts (with pigments). The most important plastid is with green chlorophyll pigment
called chloroplasts. Chloroplasts participate in the photosynthetic activity.
(f) Lysosomes—It contains hydrolytic enzymes for digestion.
BSCB-125 Cell Biology
